# UNDF: UNDF-2026-000000907
--- a/src/gui/gui-nicklist.c
+++ b/src/gui/gui-nicklist.c
@@ -596,7 +596,12 @@
  *
  * Return pointer to new nick, NULL if error.
  */
-
+/*
+ * CWE-407: gui_nicklist_search_nick() performs O(N) linear scan
+ * through the nick linked list for dedup check on every add.
+ * When bulk-adding N nicks (e.g., joining a large IRC channel),
+ * this yields O(N^2) total work.
+ * Fix: maintain a hash table of nick names per buffer for O(1) lookup.
+ */
 struct t_gui_nick *
 gui_nicklist_add_nick (struct t_gui_buffer *buffer, long long id,
                        struct t_gui_nick_group *group,
@@ -604,7 +609,8 @@
 {
     struct t_gui_nick *new_nick;

-    if (!buffer || !name || gui_nicklist_search_nick (buffer, NULL, name))
+    /* O(N) linear scan for dedup => O(N^2) when adding N nicks */
+    if (!buffer || !name || gui_nicklist_search_nick (buffer, NULL, name))
         return NULL;

     new_nick = malloc (sizeof (*new_nick));